TAMPA, Fla. – U.S. Senator Bill Nelson says he expects University of South Florida researchers to find another cemetery at the now closed Dozier School for Boys in Marianna.

So far USF anthropologists have uncovered 55 bodies, 24 more than state records said were buried at the controversial school. All of the remains have been located in and around a cemetery at the school known as "Boot Hill."

But Nelson told reporters on Tuesday that given the school's vast size and 111-year history, he believes USF researchers could unearth more startling discoveries.

"I think eventually they're going to find another cemetery, because back then they did not bury the two races together and so no telling what stories are going to unfold," Nelson said.

Dozier covers some 1,400-acres and while researchers have used ground penetrating radar and even cadaver dogs, they say the search for additional bodies is challenging.

"When you're looking for skeletal remains of children from years ago, you could be next to it and miss it," USF Professor of Anthropology Dr. Erin Kimmerle said.

Based on skeletal remains already uncovered, Kimmerle also released a sketch Tuesday of what one of the boys they exhumed likely looked like. The sketch is of an unidentified 8 to 10-year-old African American boy.

Officials On Tuesday also didn't rule out the possibility of asking for another permit to continue working at Dozier past August. The current state permit expires on August 6.

Meanwhile, the Hillsborough County Sheriff's Office is helping USF researchers look for relatives of 36 boys known to have died at Dozier. Officials want to track down family members for DNA testing to help positively identify remains exhumed at the school.